Distinct mantle sources for Pliocene-Quaternary volcanism beneath the modern Sierra Nevada and adjacent Great Basin, nor

A swath of young volcanic activity occurs in the region north of Lake Tahoe, USA, to as far east as Battle Mountain, Nevada. The goal of this work by Brian Cousens and colleagues is to describe how the geochemistry and inferred origin of the lavas changes from west to east.

They show that volcanic activity in the Lake Tahoe-Reno-Carson City area is derived largely from melting of the mantle lithosphere underlying the Sierra Nevada. Here, the lithospheric mantle may be melting as a result of hot mantle rising beneath it. However, similar-aged volcanic fields around Fallon and at Battle Mountain are composed of lavas generated largely from the shallow convecting upper mantle beneath the lithosphere. These eastern volcanic fields, situated within the Great Basin, appear to overly lithospheric mantle that has lost its ability to melt, so for volcanism to occur the underlying convecting mantle must be shallow enough to melt.

The authors note that the potential for future eruptions remains throughout this broad region, based on the youth of the volcanic fields and the abundant seismicity in the area.

More information:
Brian Cousens et al., Ottawa-Carleton Geoscience Centre and Isotope Geology and Geochronology Research Facility, Dept. of Earth Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada. Posted online 11 April; doi: 10.1130/GS741.1

Provided by Geological Society of America